1. Field of the Invention
The present invention relates to an air conditioning system designed to be mounted on the roof of a vehicle such as a bus.
2. Description of the Related Art
In conventional air conditioning systems that are designed to be mounted on the roof of a vehicle such as a bus, a fan and a motor are placed horizontally on the roof in such a manner that they do not overlap a condenser vertically due to the restriction on the height of the vehicle. FIGS. 9 and 10 show examples of the conventional layout of the air conditioning system.
Namely, according to the layout of a condensing unit portion A of an air conditioning system shown in FIG. 9, a condenser C of a plate fin and tube type is placed on the surface of the roof of a vehicle in such a manner that air inlets and air outlets are situated horizontally, and fans and motors D are placed on both sides of the condenser. In addition, a cooling unit portion B is placed adjacent to the condensing unit portion A in a longitudinal direction of the vehicle.
Additionally, in FIG. 10, a similar plate fin and tube type condenser C is used in a condensing unit portion A of an air conditioning system, which is divided into two condenser portions in a transverse direction of the vehicle, and fans and motors D are placed centrally between the divided condenser portions with air inlets and oriented in the transverse directions of the vehicle. Similarly to the example in FIG. 9, a cooling unit portion B is placed adjacent to the condensing unit portion A in the longitudinal direction of the vehicle.
According to the layouts of the conventional air conditioning systems which are overlaid on the roof of the vehicle as shown in FIGS. 9 and 10, while the height of the units can be reduced, the longitudinal or transverse dimension thereof becomes large. In addition, the air inlets of the condensers are not oriented to the front of the vehicle, and hence a ram pressure produced while the vehicle is running cannot be utilized effectively, this causing a problem that the amount of air drawn into the condenser cannot be increased.
The present invention was made in view of the aforesaid problem, and an object thereof is to provide an automotive air conditioning system which can reduce the longitudinal dimension of a condensing unit portion so as to make the condensing unit portion compact and which can effectively utilize a ram pressure produced while the vehicle is running so as to increase the amount of air drawn into a condenser, whereby the discharge pressure of a compressor can be reduced while increasing the coefficient of performance (COP) thereof, thereby making it possible to largely reduce the load power applied to an engine of the vehicle.
In addition, according to the construction of the automotive air conditioning system of the present invention, as a cooling unit portion and the condensing unit portion are mounted on the roof of the vehicle so that running air can effectively drawn into the condensing unit portion, foreign matters are easily collected in a condenser roof and upstream of a core portion of a condenser, whereby the performance of the condenser is reduced and the pressure of a refrigeration cycle is increased, this leading to a risk that the equipment fails. Due to this, another object of the present invention is to provide an automotive air conditioning system adapted to be mounted on the roof of a vehicle in which the foreign matters, that do collect, can be removed easily.
According to an aspect of the present invention, there is provided an automotive air conditioning system wherein a condenser of a condensing unit portion is inclined in a longitudinal direction of the vehicle and a condenser fan is provided directly above the condenser, and wherein an air inlet to the condenser is disposed in front of the condenser and an air outlet from the condenser is disposed above the condenser, whereby the longitudinal dimension of the condensing unit portion can be reduced so as to make the condensing unit portion compact. In addition, the amount of air drawn into the condenser can be increased by making effective use of a ram pressure produced while the vehicle is running, whereby the discharge pressure of a compressor can be reduced and the coefficient of performance of the compressor can be increased. Thus, the load power applied to an engine of the vehicle can be largely reduced.
According to another aspect of the present invention, there is provided an automotive air conditioning system, wherein the condenser is inclined downwardly from the front toward the rear of the vehicle, whereby the increase in the amount of air drawn into the condenser can be utilized most effectively.
According to a further aspect of the present invention, there is provided an automotive air conditioning system, wherein the condenser fan is placed horizontally, whereby the height of the vehicle can be reduced.
According to an aspect of the present invention, there is provided an automotive air conditioning system, wherein a unit cover for covering the condenser and the condenser fan is opened at the front and is closed at the rear and on both sides the unit cover, whereby the amount of air drawn in can be led to the condenser effectively without wasting any of the air so drawn in.
According to another aspect of the present invention, there is provided an automotive air conditioning system wherein a position, where the condensing unit portion is disposed, is specified to be a portion of the roof of the vehicle such as a bus where the flow of air flowing along the roof while the vehicle is running becomes a laminar flow, whereby the flow of air can be drawn into the condenser effectively.
According to a further aspect of the present invention, there is provided an automotive air conditioning system, wherein the condensing unit portion is disposed rearward of the first two thirds of the overall length of a vehicle, such as a bus, in the event that an upper portion of a distal end of the vehicle is formed into an edge shape, whereby the condensing unit portion can be disposed at not an area on the roof where the flow of air becomes a turbulent flow but an area on the roof where the flow of air becomes a laminar flow, and the flow of air can be drawn in the interior of the condensing unit portion constantly and effectively.
According to an aspect of the present invention, there is provided an automotive air conditioning system wherein the inclination angle of the condenser is restricted substantially to 6 to 12 degrees, and this range of the inclination angle allows the flow of air to be drawn into the condenser effectively without increasing the height of the vehicle.
According to another aspect of the present invention, there is provided an automotive air conditioning system wherein the air inlet to the condenser is covered with a net, and wherein a notch is formed in a vehicle frame for use in mounting the automotive air conditioning system on the roof of the vehicle in the vicinity of the rear of the condenser, whereby, as large foreign matters are captured by the net whereas small foreign matters are discharged from the notch in the vehicle frame to the outside thereof by virtue of running air, the reduction in the performance of the condenser due to the collection of foreign matters therein can be prevented.
According to a further aspect of the present invention, there is provide an automotive air conditioning system further comprising a control means for a condenser fan motor, wherein the condenser fan motor is forcibly switched off every a given time by the control means, whereby foreign matters collecting in a condenser room can be discharged from the notch by reducing an amount of the running air entering the condenser that is discharged through the condenser and increasing a portion of the same running air that is discharged from the notch in the vehicle frame.
According to an aspect of the present invention, there is provided an automotive air conditioning system, further comprising a control means for a condenser fan motor, wherein the condenser fan motor is caused to turn in a reverse direction for a given time by the control means after the automotive air conditioning system has been activated, whereby the foreign matters can forcibly be discharged from the notch in the vehicle frame.
According to another aspect of the present invention, there is provided an automotive air conditioning system, further comprising a control means for a condenser fan motor and a pressure detecting means for detecting the discharge pressure of a compressor, wherein the condenser fan motor is controlled according to the discharge pressure of the compressor. Namely, when foreign matters collect and the discharge pressure increases, the condenser motor is switched off, so that the foreign matters that collect are discharged from the notch.
The present invention may be more fully understood from the description of preferred embodiments of the invention, as set forth below, together with the accompanying drawings.